Prosecutors evaluating evidence in the royal phone message hacking case were faced with so many potential offences that they deliberately limited the number of charges to prevent the inquiry becoming "unmanageable", a statement from Keir Starmer, the director of public prosecutions, said today.

Police and lawyers from the Crown Prosecution Service decided that they needed to only "properly reflect the overall criminal conduct" of the News of the World royal editor Clive Goodman and private investigator Glenn Mulcaire. So they selected just five or six potential victims.

The statement reveals that police and the CPS used a set of criteria for the selection: they chose the strongest cases; ones where there was "integrity in the data"; where corroboration was available; where charges would be representative of the pool of victims; and where the victims would be willing to give evidence.

"Any other approach would have made the case unmanageable and potentially much more difficult to prove," said the DPP. This is an approach that is adopted routinely in cases where there is a large number of potential offences."

He also confirmed that when police raided Mulcaire's office they found further evidence of interception and invoices for payments the private investigator had received from the News of the World for "research" into individuals who had no connection with the royal family, including politicians, sports personalities and other celebrities.

Coming to the conclusion that the CPS and the police properly handled the prosecution of Goodman and Mulcaire, both imprisoned at the Old Bailey in January 2007, he said it would not be appropriate to reopen the cases of the two men. But he added: "I am not in a position to say whether the police had any information on any other victims or suspects that was not passed to the CPS."

The DPP's review of the case was prompted by the outcry that followed revelations in the Guardian last week that News International had secretly paid £1m in damages and costs in three privacy cases bought as a result of phone-message hacking by Mulcaire and involving the News of the World. Earlier this week the Guardian, in evidence to the House of Commons culture select committee, handed over documentary evidence linking three News of the World journalists – including the former assistant editor, Greg Miskiw, and the chief reporter, Neville Thurlbeck – to Mulcaire and his illegal targeting of Gordon Taylor, the chief executive of the Professional Footballers' Association. Taylor was among those who settled in secret with News International, receiving £700,000 in costs and damages.

Last night's statement does not say why other News of the World journalists were not interviewed by police, apart from the implicit explanation that the prosecuting team felt that to get the convictions of Goodman and Mulcaire on the specific charges they did not need to.

The select committee will resume its inquiries next Tuesday by calling the former News of the World editor Andy Coulson, now the Tories' director of communications. He has consistently said he did not know anything of Goodman's illegal hacking activities, but he resigned on the basis that it happened on his watch.